• Offshore operations
• Desert landings
• EMS operations in built up areas and confined spaces
• Alpine operations
• Ship landings
• Fire fighting
• Under slung load carrying
• Visuals degraded by smoke, swirling and driven snow, etc
• Unfamiliar landing sites

Unfortunately, as a result, any review of helicopter accident statistics makes for sobering reading, with cognitive overload and inadvertent (or unexpected) entry into IMC, and other disorientating illusions featuring heavily in the descriptions.
 
Over 20% of helicopter accidents occur in training. Additionally a very high proportion of helicopter accidents overall have reported Spatial Disorientation (SD) as a contributory factor if not the main cause of the incident. These two facts alone suggest the need for extensive training. Simulator training in particular allows the pilot to fly to and beyond the edges of the flight envelope to test skills and understand thresholds. However, whilst there are many simulators out there designed to support instrument ratings, type conversions, recurrent training, mission rehearsals etc and that provide adequate to excellent training in how to fly the aircraft, operate systems and deal with incidents/emergencies, few provide comprehensive training in SD. SD skills are all very perishable and whilst awareness helps, there is no substitute for regular practice in a suitably equipped training device.
 
A key theme that recurs in discussions with experienced helicopter crews is that there is almost always some operationally related distraction that precedes a real SD event. This distraction is invariably related to a systems issue such as a failure or malfunction, an urgent communication with rear cabin crew (such as paramedics with a deteriorating patient) or a navigational requirement. Consequently, any simulation environment that aims to provide SD training and familiarity must be capable of replicating a similar level of operational loading in order to recreate the distractions that occur in practice.
 
This doesn’t necessarily mean that the cockpit has to be a type-specific replica of the aircraft flown on station, but it does mean that it has to be a good, recognisable representation of a modern helicopter with a typical, modern, (preferably glass) cockpit and avionics suite and twin seat, side by side configuration. This needs to be done in part for realism but also so that Crew Resource Management (CRM ) issues related to SD can be addressed and rehearsed. In conjunction with realistic hardware, the flight and systems modelling must allow for realistic fault/ malfunction injection, together with performance and handling characteristics to support a multitude of circumstances such as One-Engine-Inoperative OEI, autorotation and the aerodynamics associated with flying near ridges, confined area landings, cliff faces and a variety of elevated platforms. Similarly, although databases don’t need to be extensive in terms of geographic area, they do need to be feature-rich and appropriate for the environment and role being modeled.
 
Profiles should include realistic weather, strobe light rebound, fog punch through, recirculation of snow and dust and the effects of swirling and/or driven snow. The visuals need to provide a representative field of view – at least +20, -40° vertically and at least 210° in azimuth – for good peripheral cues specifically to support hovering as well as other flying manoeuvres. Projection refresh rates should be at least 60Hz even for detailed scenes and during spot turns. Spray, downwash and dynamic sea surface including the effects of wind lanes are important for low level off-shore work.
 
A high fidelity motion platform, preferably a 6+1 degree of freedom unit (standard 6 DoF plus continuous yaw), capable of generating specific SD illusions and realistic simulation of the motion environment associated with a loss of yaw control should be used. Outside world visuals and cockpit lighting should be NVG compatible to support high quality NVG training and for replicating the disorientating effects that occur whilst using that equipment.

Steve Jackson is the head of ETC’s Helicopter Training Products Division. He brings over 30 years experience of aeronautical engineering, including the use of simulators for various R&D activities, simulator technology development and simulator design. Most recently Steve was a director of cueSim Ltd where he was primarily involved in the development of a range of helicopter simulators. Steve’s career began in the aircraft maintenance and installation end of the business as Ministry of Defence aircraft engineering apprentice and grew through that experience into design and stress analysis related to the installation of experimental equipment on aircraft. Continuing to work for the government in the UK, he was placed on the team which developed and used for research purposes one of the biggest simulators ever built and this work ignited his interest in simulation technologies and applications. There he was exposed to some of the most ground breaking simulator technology and techniques of the times and considers himself fortunate to have working with some of the most accomplished scientists in the industry.

New to ETC, Steve is a native of England. He has drawn his experience from a background that began in practical aircraft engineering via an apprenticeship. He has several Aeronautical Engineering qualifications and an honors degree in mechanical engineering.

Steve initially came to ETC through some consultancy work which then evolved into this newly created position to capitalize on his background and experience in helicopter simulation technology. Of his career, Steve says,

“Throughout my career I’ve been lucky to have been placed in a variety of uniquely interesting roles. I’ve tended to take interesting and challenging opportunities as they’ve arisen rather than have a highly detailed career plan and fortunately to date I’ve found that new, motivating and stimulating paths have opened up along the way without me really consciously deciding to look for them.

Since coming to ETC a little more than a year ago, Steve has jumpstarted this division and spearheaded the effort to bring ETC’s helicopter simulation technologies to the forefront of the industry. He believes that there is going to be more use of helicopters world-wide in both civilian and military applications and as a result sees an increasing need to place more of an emphasis on training to improve safety and operational readiness.Spatial Disorientation in particular is not currently well addressed or understood in the helicopter training business and Steve believes that there are real opportunities to marry ETC’s knowledge and capabilities to the more traditional training devices to produce some innovative and unique products.

“This is a tremendous growth area in the simulation business. Further and more specific to ETC’s strengths, it’s easy to get disorientated in a helicopter and there’s not that many companies that can produce high fidelity helicopter simulators so ETC really has the pertinent knowledge and skills necessary for addressing this critical issue.”

As an avid fan of Rugby, Steve can be found watching it when not traveling the world on behalf of ETC. Additionally Steve loves fishing, camping, hiking and music. For the last ten (10) years he has also been an active part-time member of his local fire and rescue service.

By Michael Newman
Research Scientist, ETC

Next time you find yourself in an elevator with a few minutes to spare, close your eyes, press a random floor, and attempt to guess if you are travelling upward or downward based solely upon the sensations you perceive. Surprisingly, this challenge may be much more difficult than you think. A number of studies performed both in helicopters and vertical motion simulators have demonstrated that humans suffer from a fundamental inability to integrate inertial acceleration cues along a gravitationally vertical axis.

During Malcolm and Jones’ 1973 experiment aboard a computer-controlled helicopter [1], blindfolded subjects were asked to report their motion perception during pre-programmed sinusoidal oscillations of varying frequency and amplitude. While subjects were aware of vertical displacement, they could indicate the proper direction of travel only slightly better than chance. Some subjects even reported translating several hundred feet in the opposite direction of actual motion.

In an earlier study, Walsh and colleagues [2] found that subjects could be oscillated through large vertical distances without perceiving any motion at all.

This inherent deficiency in vertical distance estimation is in large part a direct consequence of the dynamics and relative orientation of the otolith organs located in bony labyrinth of the inner ear. In the absence of vision, the utricle and saccule organs of the otoliths are primarily responsible for providing linear motion sensation in humans and mammals. Situated between the semicircular canals and the cochlea, these organs are approximately perpendicular, and respond primarily to the horizontal (utricle) and vertical (saccule), components of the gravito-inertial force (the summation of gravity and any inertial acceleration) applied to the head.

From Selva [3], “Both the saccule and utricle are flat layered structures (Fig. 1). The top layer [...] consists of calcium carbonate crystals called otoconia, the middle layer consists of a gelatinous matrix called the otolithic membrane, and the bottom layer consists of a bed of hair cells known as the macula that is rigidly attached to the skull and therefore moves with the head. The hair cells are anchored in the macula whereas their cilias extremities are embedded in the otolithic membrane.”

Figure 1. Physiology of a macula. Hair cells are embedded in the macula and measure the deformation of the otolith membrane caused by the motion of otoconia with respect to the head. Figure reproduced from Aviation Medicine http://www.avmed.in/2011/03/orientation-in-aviation-vestibular-apparatus-2/.

Relative shearing motion and density differences between these layers cause the extremities of the hair cells (the cilia) to displace. These displacements generate receptor potentials in the hair cells, and in turn transcode electrical signals to the brain. Each receptor cell has specific direction of maximum excitability. Motion along this direction will produce the greatest frequency of signals to the brain (Fig 2).

Figure 2. Location of the utricle and saccule and orientation of the hair cells on the maculae of the otolith organs. The arrows represent the local direction of enhanced sensitivity of the hair cells. Figure reproduced from Selva 2009 [3].
Unfortunately for pilots of helicopters, and other vertical take off and landing (VTOL) vehicles, very few of these enhanced sensitivity directions appear to align with the gravitationally upright long-body-axis. Thus, in response to a vertical acceleration, only a small fraction of possible otolith hair cell signals will be sent to the brain and used to estimate orientation and motion. It is theorized that this paucity of vertical representation may be responsible for our innate inability to estimate vertical motion.

Whatever the physiological root cause may be, this severe limitation poses many challenges for the VTOL pilot. During degraded visual conditions, especially due to brown out/white out, small errors of vertical position estimation can pose extreme dangers during mission critical tasks (i.e. takeoff, landing, and hovers). Proper training is required to teach pilots to ignore these convincing, yet erroneous seat-of-the-pants sensations, and instead trust and relay solely upon their instrumentation. Other perceptual challenges such as undetected lateral drift[1], or visually induced linear vection[2], are also produced during these degraded visual conditions and can further exacerbate feelings of disorientation.

Engineers and scientists at ETC and the NASTAR Center continue to develop training and research platforms to explore these complex phenomena. Advanced devices such as the GL-6000, Gyro IPT3 eFOV and HeloFlight SD allow pilots to experience the disorienting effects of these illusions in isolation or tandem, during simulated, mission based training profiles. Specifications and further information can be found here: www.etcaircrewtraining.com

REFERENCES

[1] Malcolm, R., and Melvill Jones, G. (1973) Acta Otolaryng 77, 274-283
[2] Walsh, E.G. (1964) Experimental Physiology 49, 58-65
[3] Selva, P. (2009) PhD Thesis, University of Toulouse
[4] Dichgans, J., and Brandt, T. (1978) Handbook of Sensory Physiology (Vol 3) 756-804

[1] Undetected lateral drift can result from small, sub-threshold, lateral acceleration components that are insufficient in magnitude to produce the shear force needed to displace the cilia and excite the otolith hair cell neuron. This undetected movement, usually occurring during prolonged helicopter hover, can shift a vehicle’s relative position with the ground and impair a pilot’s ability to safely avoid obstacles and land the aircraft.
[2] The term vection is used to describe a visually induced sensation of self-motion [4]. For low-flying helicopters, self generated motion can result from the moving visual field generated by the rotor wash. This sensation can be both compelling and very disorientating.

For a limited time, ETC is inviting qualified pilots to be a part of a select group of aviation professionals to participate in a research project to evaluate all aspects of the GL-4000 simulator for upset recovery training and research. This focus group will fly in the GL-4000 flight simulator installed at its subsidiary, the National Aerospace Training and Research (NASTAR) Center’s test facility from June through August, 2011. Information on how to register as a participant can be found at http://www.etcadvancedpilottraining.com/free-training.

Due to the increasing automation of commercial aircraft, pilots have become increasingly dependent upon automated systems and do not have the opportunity to regularly practice and develop the airmanship skills necessary to recover from out of the normal flight envelop conditions. The GL-4000 provides “stick time” and valuable hands on experience to pilots, useful when the autopilot turns off during a flight. By using G-Pointing, the GL-4000 puts the pilots under the same physiological effects they feel while actually flying an aircraft. This enables pilots to better understand how it feels to be disoriented and prepares them for the potential upset in an actual flight.

The GL- 4000 flight simulator has a 10 foot planetary arm and an electro mechanical motion drive system and provides 360⁰ of continuous rotation in 4 axes of motion: Planetary, Yaw, Roll, and Pitch. The electro mechanical motion drive system supports the generation of G forces with a maximum G level of 4 G’s at mean onset rates of up to 1 G/second. This motion profile stresses the pilot just as he would be stressed while flying the real aircraft. This is a stark contrast from traditional 6 Degree of Freedom (DoF) motion systems which only provide transient rotational acceleration cueing to the pilot that frequently proves inadequate and supports counterproductive training. Thus, pilots are better prepared when they step into the cockpit for a live flight.

The GL-4000 flight simulator offers a flexible and cost efficient method to safely conduct upset recovery training in an authentic sustained G, continuous motion. This allows the pilot to develop recovery skills that directly transfer to the aircraft in a safe environment. The flexibility of the GL-4000 flight simulator allows trainees to practice flight in any weather, on any day and at any time. Motion profiles are offered from a standard bank, developed in part by re-creations of specific past upsets documented and recorded by the National Transportation and Safety Board (NTSB) or can be custom designed to address each Client’s unique requirements.

ETC, Aircrew Training Systems (ATS) division markets the GL-4000 flight simulator worldwide. The GL-4000 cockpit can be configured for any international aircraft, commercial or military with an adapted aeromodel to emulate each craft’s individual performance envelope.

More detailed specifications for the GL-4000 flight simulator and other Aircrew Training Systems, please contact Robin Valinski, Sales and Marketing Coordinator, Aircrew Training Systems (ATS) group.

The NVTS consists of a computer-based training system with automated training programs for unaided vision and Night Vision Goggle (NVG) flying in the night environment and a Terrain Model Board designed to replicate the Saudi Arabia terrain. The NVTS will be installed in a theater-style classroom specifically designed for night vision training in the purpose-built RSAF areomedical training center.

The RSAF will use ETC’s NVTS to train their pilots how to safely and effectively conduct unaided vision night flying operations as well as the safe use of their own NVGs (NVGs are not provided with ETC’s NVTS). This type of training complements the RSAF human factors training program by training their pilots in the procedures and techniques for coping with the hazards associated with night flying. The RSAF is committed to the professional development and safety of their pilots through modernization of its aviation physiology training program. ETC is proud to be the supplier of state-of-the-art aviation physiology training equipment to the RSAF.

More detailed specifications for the NVTS and other Aircrew Training Systems is available by contacting: Robin Valinski, rvalinski@etcusa.com, Sales and Marketing Coordinator, ATS at ETC, 125 James Way, Southampton, PA 18966, USA. Phone: 215 355 9100 extn.1501